Circumstances – widespread disease, for example – could see the price of meat exceed these products for periods of time. At which point these products could become contenders on factors of price, but as soon as the market starts to shift the price of meat will fall on the decrease in demand, and you're back to square one. Especially as meat has lag time to market so the price will fall further than you might expect before meat producers are able to pull back on production. There is nothing to keep people eating these products if there is nothing to differentiate them in the market.
The real value proposition is that it is different. A new food option to choose from. If it can be made great, where it is craved as much as meat, then they might have something. Until then, I can see why they are struggling.